(1) Field of the Invention
The present invention relates to the handling of dirt-laden gases and particularly to the separation of particulate matter from such gases prior to their release to the ambient atmosphere through a silencer and/or filter. More specifically, this invention is directed to a dust separator and especially to a separator for installation in a pressure equalization conduit or a shaft furnace charging installation. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in the environment of a blast furnace. Modern blast furnaces operate with a relatively high counter-pressure. The material with which the furnace is charged must be delivered thereto, during furnace operation, from the ambient atmosphere. This is accomplished by providing charging bells or storage hoppers which may be alternately opened to the atmosphere for loading with charge material and subsequently sealed from the atmosphere and pressurized to the level of the pressure existing within the furnace whereupon a discharge valve may be opened and the charge material released into the furnace. A furnace charging installation employing a pair of intermediate storage hoppers which are alternately pressurized and depressurized may be seen from U.S. Pat. No. 3,693,812. In the referenced patent the pressure within the intermediate storage hoppers, which are indicated at 2 and 2', is reduced to atmospheric by means of pressure equalization valves indicated generally at 8 and 8'.
Environmental configurations require that, when the pressure within a storage hopper of a shaft furnace charging installation is to be reduced to atmospheric, noise and release of particulate matter to the atmosphere be held to an acceptable level. These requirements, in turn, dictate that the conduits through which the gas travels in escaping from the hopper be positioned high above the work area and be equipped, at or adjacent their discharge ends, with silencers and/or filters. The comparatively inexcessible location, and the dangerous environment, renders the service of these silencers and/or filters difficult.
The atmosphere within a furnace charge storage hopper, for example one of the hoppers 2 of U.S. Pat. No. 3,693,812 is very dirty and may, at the time pressure equalization is required, be as high as 3 bars or more. Thus, when the pressure equalization valve is opened, to reduce the chamber pressure to atmospheric, there will be expansion and, accordingly, considerable cooling of the dust-laden gases which escape through the pressure equalization system conduit. This cooling results in the condensation of water on the elements of the silencers and/or filters exposed to the gas stream. The condensed water may freeze thus blocking the silencers and/or filters thus preventing or slowing the pressure equalization cycle. If the condensate does not freeze, dust entrained in the escaping gases will be wetted thereby thus forming an encrustation of dirt which interfers with proper operation of the silencers and/or filters. In either case, the silencers and/or filters must be periodically cleaned or removed and replaced and this is a difficult and time consuming task.